Magnetic drive systems and methods for a micromachined fluid ejector

Abstract

The systems and methods of the present invention operate by magnetically driving a fluid ejector. In various exemplary embodiments, a primary coil and a secondary coil are situated in the ejector. The ejector has a movable piston usable to eject fluid through a nozzle hole. The piston may be resiliently mounted and biased to an at-rest position. A drive signal is applied to cause current to flow in the primary coil. The current flow generates a magnetic field that induces a current in the secondary coil. Either the primary coil or the secondary coil or associated with the piston and the other is associated with a fixed structure of the ejector. As a result, a magnetic force is generated that pushes the piston either toward a faceplate so that a drop of fluid is ejected through the nozzle hole in the faceplate or away from the faceplate so that fluid fills in a fluid chamber between the piston and the faceplate. When the drive signal is turned off, the piston resiliently returns to its at-rest position, thereby either refilling the ejected fluid or ejecting a drop of fluid through the nozzle hole in the faceplate. In various other embodiments, the faceplate is made of a magnetic material, such as a ferrous material, or is coated with or connected to a magnetic material. A second primary coil or a permanent magnet may be included in various other embodiments. In various embodiments, switching the direction of the current changes the magnetic force between attraction and repulsion.

What is claimed is:  
     
       1. A method for ejecting a fluid form a fluid ejector, comprising: 
       generating a magnetic force that moves a movable member of a fluid ejector to alter a capacity of a fluid chamber of the fluid ejector; and  
       ejecting fluid from the ejector based on the altered capacity of the fluid chamber.  
     
     
       2. The method of  claim 1 , wherein the generated magnetic force selectively moves the movable member in a first direction and a second direction opposite the first direction. 
     
     
       3. The method of  claim 1 , wherein ejecting fluid from the ejector is directly controlled by movement of the movable member by the generated magnetic force. 
     
     
       4. The method of  claim 1 , wherein generating the magnetic force comprises applying current to a primary coil to generate a magnetic field between the movable member and a fixed portion of the fluid ejector. 
     
     
       5. The method of  claim 4 , wherein a direction of the current applied to the primary coil is switched to change between an attractive magnetic force and a repulsive magnetic force the magnetic force between the movable member and the fixed portion. 
     
     
       6. The method of  claim 4 , wherein generating the magnetic force further comprises inducing a current in a secondary coil. 
     
     
       7. The method of  claim 4 , wherein generating the magnetic force further comprises using a magnetic material. 
     
     
       8. The method of  claim 4 , wherein generating the magnetic force further comprises using a permanent magnet. 
     
     
       9. The method of  claim 4 , wherein generating the magnetic force further comprises applying current to a second primary coil to generate a second magnetic field between the movable member and the fixed portion of the fluid ejector. 
     
     
       10. The method of  claim 9 , wherein a direction of the current applied to one of the primary coil and the second primary coil is switched to change the magnetic force between the movable member and the fixed portion between an attractive magnetic force and a repulsive magnetic force. 
     
     
       11. A magnetic drive system for a fluid ejector having an ejection chamber, comprising: 
       a movable member located in the ejection chamber;  
       at least one primary coil; and  
       at least one drive signal source that applies a drive signal to cause a current to flow in the primary coil;  
       wherein the current flow in the primary coil generates a magnetic field that moves the movable member within the ejection chamber.  
     
     
       12. The magnetic drive system of  claim 11 , wherein the drive signal source is arranged to switch the drive signal such that a direction of the flow of the current in the primary coil is reversible. 
     
     
       13. The magnetic drive system of  claim 11 , further comprising at least one resilient support member connected to the movable member such that the movable member is biased to a rest position when the drive signal is not applied. 
     
     
       14. The magnetic drive system of  claim 11 , further comprising a secondary coil wherein, when the drive signal is applied to the primary coil, the secondary coil is located within the generated magnetic field, the generated magnetic field inducing a current in the secondary coil, the induced current generating a second magnetic field, such that a repulsive magnetic force is generated between the primary and second coils. 
     
     
       15. The magnetic drive system of  claim 14 , wherein the secondary coil is associated with the movable member. 
     
     
       16. The magnetic drive system of  claim 15 , wherein the primary coil is associated with a fixed member of the fluid ejector. 
     
     
       17. The magnetic drive system of  claim 14 , wherein the primary coil is associated with the movable member. 
     
     
       18. The magnetic drive system of  claim 17 , wherein the secondary coil is associated with a fixed member of the fluid ejector. 
     
     
       19. The magnetic drive system of  claim 11 , further comprising a magnetic material wherein, when the drive signal is applied to the primary coil, the magnetic material is located within the generated magnetic field such that an attractive magnetic force is generated between the primary coil and the magnetic material. 
     
     
       20. The magnetic drive system of  claim 19 , wherein the magnetic material is associated with the movable member. 
     
     
       21. The magnetic drive system of  claim 20 , wherein the primary coil is associated with a fixed member of the fluid ejector. 
     
     
       22. The magnetic drive system of  claim 19 , wherein the primary coil is associated with the movable member. 
     
     
       23. The magnetic drive system of  claim 22 , wherein the magnetic material is associated with a fixed member of the fluid ejector. 
     
     
       24. The magnetic drive system of  claim 11 , wherein: 
       the at least one primary coil comprises a first primary coil associated with a fixed member and a second primary coil associated with the movable member;  
       the drive signal source is arranged to apply a first drive signal to the first primary coil to cause a first current to flow in the first primary coil and a second drive signal to the second primary coil to cause a second current to flow in the second primary coil; and  
       the first current in the first primary coil and the second current in the second primary coil generate a magnetic force that moves the movable member.  
     
     
       25. The magnetic drive system of  claim 24 , wherein the drive signal source is arranged to switch the drive signal to one of the first and second primary coils such that a direction of the flow of a corresponding one of the first and second currents is reversible. 
     
     
       26. The magnetic drive system of  claim 24 , wherein the drive signal source comprises: 
       a first drive signal source that applies the first drive signal to the first primary coil; and  
       a second drive signal source that applies the second drive signal to the second primary coil.  
     
     
       27. The magnetic drive system of  claim 11 , further comprising: 
       a permanent magnet that generates a magnetic field such that a magnetic force is generated between the permanent magnet and the primary coil when the drive signal is applied to the primary coil.  
     
     
       28. The magnetic drive system of  claim 11 , wherein the permanent magnet is associated with a fixed member.